It's very similar to Rebol and is under active development. If you like Rebol and haven't tried Red, it's worth taking a look:
https://github.com/red/red
which is a spreadsheet in 17 lines of code using the inbuilt reactive system.
https://github.com/metaeducation/ren-c
https://github.com/r3n
https://forum.rebol.info
In fact there was a Rebol conference only last month - http://2019.reb4.me/
It's very similar to Rebol and is under active development. If you like Rebol and haven't tried Red, it's worth taking a look:
https://github.com/red/red